[LeetCode] 1768. Merge Strings Alternately

You are given two strings word1 and word2. Merge the strings by adding letters in alternating order, starting with word1. If a string is longer than the other, append the additional letters onto the end of the merged string.

Return the merged string.

Example 1:

Input: word1 = "abc", word2 = "pqr"
Output: "apbqcr"
Explanation: The merged string will be merged as so:
word1:  a   b   c
word2:    p   q   r
merged: a p b q c r

Example 2:

Input: word1 = "ab", word2 = "pqrs"
Output: "apbqrs"
Explanation: Notice that as word2 is longer, "rs" is appended to the end.
word1:  a   b 
word2:    p   q   r   s
merged: a p b q   r   s

Example 3:

Input: word1 = "abcd", word2 = "pq"
Output: "apbqcd"
Explanation: Notice that as word1 is longer, "cd" is appended to the end.
word1:  a   b   c   d
word2:    p   q 
merged: a p b q c   d

Constraints:

• 1 <= word1.length, word2.length <= 100
• word1 and word2 consist of lowercase English letters.

交替合并字符串。

给你两个字符串 word1 和 word2 。请你从 word1 开始，通过交替添加字母来合并字符串。如果一个字符串比另一个字符串长，就将多出来的字母追加到合并后字符串的末尾。

返回 合并后的字符串。

来源：力扣（LeetCode）
链接：https://leetcode.cn/problems/merge-strings-alternately
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

这道题考察字符串的基本操作。我直接给代码。

时间O(m+n) - 需要合并两个字符串

空间O(m+n) - 最后返回的字符串长度

Java实现

 1 class Solution {
 2     public String mergeAlternately(String word1, String word2) {
 3         int i = 0;
 4         int j = 0;
 5         StringBuilder sb = new StringBuilder();
 6         while (i < word1.length() && j < word2.length()) {
 7             sb.append(word1.charAt(i++));
 8             sb.append(word2.charAt(j++));
 9         }
10         while (i < word1.length()) {
11             sb.append(word1.charAt(i++));
12         }
13         while (j < word2.length()) {
14             sb.append(word2.charAt(j++));
15         }
16         return sb.toString();
17     }
18 }

LeetCode 题目总结